Luminescent tube



Patented Apr. 23, 1929.

UNITED STATES PATENT OFFICE.

LUMINESCENT TUBE.

No Drawing.

This invention relates to luminescent tubes, ronsisting generally of asuitably bent glass ube filled with a conducting gas, and having lIlelectrode at each end.

The objects of the present invention are improve the colour of the lightradiated, and also to enable the tube to emit actinie rays, which areuseful for a variety of purposes.

It consists essentially of the improved construction and method ofmanufacture, hereinafter described in detail.-

The electrodes may be formed from a suitable metal such as tungsten,molybdenum,

iron, nickel or cadmium, of a high degree of purity, of any convenientshape, and may for instance be in the form shown in my United StatesPatent No. 1,600,595, dated 21st day of September, 1926.

Prior to insertion in the tube, the electrodes are preferably cleaned orscavenged in an atmosphere of hydrogen and nitrogen gas, by heating thesaid electrodes in such atmosphere to a temperature of say 700 to 800 C.

for a period of from 5 to 6 minutes. The

electrodes are then sealed in a glass tube, in which a few drops ofclean mercury have previously been dropped, the tube is then pumped to ahigh degree of vacuum say by the vacuum pump, the vacuum being in theneighbourhood of say .0001 mm. of mercury.

A small quantity of neon or other conducting gas at a. pressure of l to3 mm. of mercury is then introduced in the tube.

The electric current is then passed through the tube at an amount ofabout 2 00 to 500 milliamperes for the purpose of scavenging orcleansing the tube. The tube is then again pumped to a high vacuum.

The operation of exhaustion and filling with'neon gas may be repeated asecond time if desired.

Application filed August 26, 1927. Serial No. 215,752.

Argon gas is then introduced in the tube at a pressure varying from to 1mm. At the same time neon gas is also introduced at a pressure from 2.5mm. to 4 mm. of mercury, making a total gas pressure of 2% mm. to 5 mm.of the resulting mixture. The tube is then cut off from the pump andsealed, and is then ready for operation.

If it is desired to make use of actinic rays including violet orultra-violet rays, the tube should be made from quartz or Pyrex glass.

It Will be found that in operation, in place of the usual orange colour,the light emitted will be blue.

As many changes could be made in the above construction, and manyapparently Widely different embodiments of my invention, within thescope of the claims, constructed Without departing from the spirit orscope thereof, it is intended that all matter contained in theaccompanying specification shall be interpreted as illustrative, and notin a limiting sense.

What I claim as my invention is:

1. Luminescent tube comprising a transparent tube adapted to permit thepassage of actinic rays, a gaseous filling therein comprising a mixtureof argon and noon. and mer- 7 cury vapour, and electrodes for the tube.

2. A luminescent tube comprising a tube, having a filling of argon, noonand mercury vapour.

3. The herein described method of manufacturing luminescent tubescomprising first scavenging the electrodes, then introducing theelectrodes into the tube, then adding a few drops of mercury, thenscavenging the tube and then filling the same with a mixture of neon andargon.

In Witness whereof I have hereunto set my hand.

PAUL FRANQOIS J OSEPII LEBRUN.

